US Patent 7401706 Closure and package having child-resistant and non-child-resistant modes of operation

A closure having child-resistant and non-child-resistant modes of operation includes a plastic inner shell having a skirt with at least one internal thread, an external bead on the skirt and a circumferential array of teeth on the bead. A plastic outer shell has a skirt externally encircling the skirt of the inner shell. The outer shell has an internal bead on its skirt, a circumferential array of first teeth on one side of the internal bead, a circumferential array of second teeth on the other side of the internal bead, and at least one third engagement element adjacent to an edge of the skirt. The inner shell is positionable within the outer shell in child-resistant and non-child-resistant positions, in which the teeth on the inner skirt engage the first or second teeth on the outer shell.